Ion plating anode source



May 26, 1970 R. c. BRUMFIELD ETAL 3,514,392

' I ION PLATING ANODE SOURCE Filed March 18, 1968 JOHN T F AZOA/ZO Z'W 505M500 AGE/V7 United States Patent ION PLATING ANODE SOURCE Robert C. Brumfield, Emerald Bay, John T. Naif, Costa Mesa, and Alonzo T. W. Robinson, Huntington Beach, Calif., assignors to Automatic Fire Control Inc., South El Monte, Califl, a corporation of California Filed Mar. 18, 1968, Ser. No. 713,728

Int. Cl. C23c 15/00 US. Cl. 204-298 1 Claim ABSTRACT OF THE DISCLOSURE A helical wound coil wire, each wire coil having a cardioid shape, the cleft of each being linearly aligned with the other clefts. The wire coil advantageously is used as an anode filament structure for anode plating metal source for the commercial ion metal plating of metal parts, in a low argon gas pressure, high voltage, abnormal glow discharge.

BACKGROUND OF THE INVENTION Mattox in US. Pat. No. 3,329,601 discloses a general apparatus in which this invention may be employed. A copending patent application of this date filed by the co-inventors of this application teaches and claims further improvements in the apparatus of Mattox. The copending patent application is titled Ion Metal Plating of Multiple Parts.

conventionally, the source of anode plating metal in ion plating is a multiplicity of plating metal, hair-pin shaped clips which are manufactured specifically for the purpose, and which are individually secured to a helical coiled tungsten wire filament by mechanically compressing the clips onto the filament Wire. The hair-pin clips require a special mechanical forming step, and the attachment of multiple individual plating metal clips to a wire filament requires a large amount of labor and time. This invention teaches a process which eliminates the need for special plating metal mechanically formed shapes, and also greatly reduces the loading time required for preparing the anode Wire filament plating metal source.

SUMMARY OF THE INVENTION This invention teaches a process for preparing an anode plating metal filament source for ion metal plating which can be used in a repetitive commercial ion plating process. A uniform diameter helical coiled tungsten wire filament, or one of tantalum or molybdenum metal, is mechanically secured and electrically connected in a horizontal position with respect to the cylindrical axis of symmetry of the helix cylinder. A multiple number of the anode filaments are electrically connected and located in a plating apparatus. The horizontal filament coils are then loaded with multiple Wire lengths of the plating metal, placed inside the horizontal filament coils and supported by the coils. The lengths of the plating metal wires do not substantially exceed the horizontal helical axis length, and the number of wire lengths placed therein do not exceed the amount of plating metal which can be supported by the coil when the coil is heated to ion plating operating temperature.

The helical wound filament coil length can have a cardioid or heart shaped cross section for each coil revolution, as well as a circular cross section. The linearly aligned dimples or clefts formed by the heart shaped single coils are located at the top of the horizontally aligned coils, and the multiple dimples provide a set of aligned recesses in which plating metal Wire lengths can be loaded and held.

3,514,392 Patented May 26, 1970 Included in the objects of this invention are:

First, to provide a process for rapidly preparing a multiplicity of metal plating anode filament sources for commercial ion plating of metal parts, with consequent reduction in labor time and costs.

Second, to increase the useful working life of helical wound anode wire filaments required in commercial metal ion plating, by reducing the mechanical work done on the filament wires.

Third, to reduce the mechanical imperfections in metal plating on parts, by reducing the rough boiling of plating metals olf the heated anode filament.

Other objects and advantages of this invention are taught in the following description and claims.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 in detail, the helical wound anode plating metal source 1 is shown to have a helical wound, coiled wire cylinder 3 of uniform diameter. The Wire is selected from the class of tungsten, molybdenum and tantalum. The cylindrical axis of symmetry 5 is horizontally disposed in the ion plating apparatus. The termini 6 of the source 1 are electrically connected to the anode power source, and termini 6 are also mechanical filament supports. The plating metal 7, which is in wire or strip structure shape, rests inside the cylinder 3 at the bottom 8 of the cylinder 3. The metal wire or strip 7 is shown bent at right angles to form the pair of wire termini 9, the termini 9 operate as hooks to prevent the wire or strap 7 from accidentally sliding off the wire cylinder 3.

In a further modification, the anode plating metal source 30 of FIGS. 3 and 4 has a helical wound, uniform diameter coiled wire cylinder 31. The individual wire coils 32 of the cylinder 31 have a cardioid shape, the cardioidal cleft 33 of each coil 32 being uniformly aligned at the top of the multiplicity of coils 32, with respect to the horizontally disposed cylindrical axis of symmetry 34. The multiple lengths of plating metal wire or strip 35 are sized in length to extend the length of cylinder 31, and to have right angle bent termini 36 which prevent the Wire or strip 35 from accidentally sliding off the top of the aligned clefts 33. The cylinder 31 has termini 37 which are both electrical conductors and mechanical supports for the anode source 30.

The amounts of wire lengths 7 and 35 which can be disposed in the anode plating metal sources 1 and 30 respectively are limited to the amounts of plating metal which can be melted and cohered to the respective Wire cylinders 3 and 31 by interfacial tension, at the required filament source operating temperature.

In an ion metal plating process as taught in our copending application of this date, titled Ion Metal Plating of Multiple Parts, we teach an apparatus in which the anode source of this invention can be utilized to reduce labor and material cost in a commercial ion plating process. By providing a simple loading process for the plating metal 7 and 35, or the like, in this invention, the necessity of mechanically crimping on the plating metal U or hair-pin type clip is eliminated. The fracturing and breaking of the new or used, friable metal wire filament of tungsten, molybdenum or tantalum is eliminated, as no mechanical work is done on the filaments, as by clamping clips.

In practice an ion metal plating apparatus is operated with the anode plating metal source 1 or 30 powered through the respective termini 6 or 37 with low voltage (2 to 120 volts AC) energy to maintain the respective cylinders 3 and 31 at the required high temperature. A normal anode plating source 1 or 30 operating temperature is fixed by the argon gas pressure in the abnormal glow discharge. At a typical argon gas operating pressure of 10 micron, the vapor pressure of the hot, melted metal formed from the metal lengths 7 and 35 should be approximately equal to the vapor pressure of the argon gas, i.e., 10 microns. Table I lists the temperatures of a number of metals which melt, wet and vaporize as desired in this process and apparatus of this invention. The metals can be economically formed in wire or strip lengths and are very useful plating metals in this process.

TABLE I Temperature C.)

Metal: (at 10 micron vapor pressure) Al 996 Cu 1273 Au 1465 Fe 1447 Pb 718. Ni 1510 Pt 2070 In practice, the weight of wire lengths 7 and 35 are limited to the quantity of plating metal which can melt, travel around the wire coils of the filaments and uniformly wet the filament metals by interfacial tension effects, without dropping off the wire coils. The horizontal disposed filaments are more uniformly wet by plating metal and are not prone to overheat. Rough boiling or sputtering off of the molten plating metals from the sources 1 and 30 are minimized by better control of filament heating rate.

Both of the plating metal sources 1 and 30 have the labor saving advantages in a commercial process of very short loading time which requires a very low level of technical skill. In general, the less physical work done on the cylinders 3 and 31, the less filament breakage, as the cylinders become fragile after a few temperature cycles in a plating apparatus.

By using the process and anode plating source taught in this invention, the useful life of a helical wound, coiled wire heating cylinder is increased, typically from four cycles to eleven cycles before the filament wire breaks.

Any plating metal which can be formed in wire or strip form, melts and wets the tungsten, molybdenum or tantalum wire heating filament, can be used in this invention. Additional plating metals which are useful in this invention are antimony, barium, beryllium, bismuth, calcium, cadmium, germanium, indium, magnesium, manganese, palladium, silver, tellurium, titanium, vanadium and zinc.

Obviously many modifications and variations of this improvement in ion plating anode source can be made in the light of the above teachings. It is therefore understood that within the scope of the appended claims, this invention can be practiced otherwise than as specifically described.

We claim:

1. The anode filament source for metal plating in a vapor disposition process comprising: a helical wound, coiled wire cylinder having a pair of termini, each individual wire coil in said cylinder having a cardioid shape, the cardioid cleft of each individual wire coil being linearly aligned with every other cardioid cleft, said wire being selected from the class of tungsten, molybdenum and tantalum and a plateing metal wire selected from the class of metals consisting of A1, C0, Cu, Ge, Au, Fe, In, Pb, Ni, Pd, Pt, Ag, Sn, Ti, V, and Zr, is disposed in a plurality of said clefts.

References Cited UNITED STATES PATENTS 3,257,305 6/1966 Varga 204l92 3,271,285 9/1966 Skoda 204-192 3,329,601 7/1967 Mattox 204-298 ROBERT K. MIHALEK, Primary Examiner US. Cl. X.R. 313-343 

